PON system and logical link allocation method

Abstract

A PON (Passive Optical Network) system, which is installed in an access network for connecting a user terminal to a network and can improve the utilization efficiency of the network, is provided. The PON system comprises an OLT (Optical Line Terminal) and at least one ONU (Optical Network Unit), and the OLT connects with the network and the ONU accommodates a user terminal and connected to the OLT via an optical fiber. A logical link generation or deletion condition table and a logical link identifier management table are provided for allocating logical links to be used between the OLT and the ONU. The logical link generation or deletion condition table defines generation or deletion conditions of logical link depending on the traffic (or service) class indicated by contents of a packet passing through the PON system. The logical link identifier management table contains logical link information to be allocated, and a content of this table is added or deleted by the control with referring to the logical link generation or deletion condition table. Whenever the packet is received, the PON system peeps in the contents of the packet, and allocates an appropriate logical link in accordance with the contents.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a PON (Passive Optical Network) system and a logical link allocation method. [0003] 2. Description of the Related Art [0004] An access network such as an FTTH (Fiber To The Home) that provides Internet connections employing optical fibers is known. The optical fiber allows high-speed communications but has higher introduction costs than that of copper wire, which impeded the spread of the FTTH. [0005] Thus, a PON system in which one optical fiber is shared among plural users to suppress the introduction costs of FTTH is well known. The configuration of a typical PON system is disclosed in Japanese Patent Application Laid-Open No. 2004-312633. FIG. 18 is a control block diagram of the typical PON system 100 as disclosed in this document. The PON system 100 comprises an OLT (Optical Line Terminal) 102 for connecting to a network 101, and a plurality of ONUs (Optical Network Unit) 108 e...

AI Technical Summary

Benefits of technology

[0016] The exemplary feature of the present invention is to provide a PON system and a logical link allocation method in which the utilization efficiency of the network can be increased without requiring the extra load.

[0021] In the invention, the logical link is dynamically allocated in accordance with the contents of the packet passing through the PON system. Accordingly, no logical link not actually used is set wastefully. That is, the use of logical link can be concentrated on the traffic actually required, so that the utilization efficiency of the network can be increased.

[0022] Also, the dynamic control for logical link allocation is automatically performed by judging whether or not the contents of the packet passing through the PON system are matched with the update conditions in a condition definition table defining the update conditions for adding or deleting the logical link. That is, in the invention, the system operator only needs to set the condition definition table. Accordingly, the invention makes it possible to easily increase the utilization efficiency of the network without forcing the system operator to take the extra load.

Problems solved by technology

The optical fiber allows high-speed communications but has higher introduction costs than that of copper wire, which impeded the spread of the FTTH.

However, the non-patent document does not particularly disclose the method for allocating the logical link identifier.

Accordingly, in the case where the logical link identifier is individually allocated for each service, such as multicast distribution, video on-demand or voice, there is a risk that the first to third problems as described below may occur.

Since the logical link identifier is statically allocated, an up band secured by the logical link is wasted when the allocated logical link is not used.

Accordingly, there is a risk that the up band is compressed, and the utilization efficiency of the network is lowered.

Accordingly, it takes a considerable amount of time to change over the services, and it is expected that the operator is forced to make a complex setting change operation.

Further, if the setting change operation is complex, it is anticipated that a situation such as a service interruption due to an artificial mistake occurs.

Accordingly, the QoS of the network can not be fully secured.

However, even with this method, the third problem is not still solved.

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